266 HYDROCHARIDACE^. Vausneeia. 



Plant rooting in the mud, and producing stolons. Leaves 1-2 feet or more in length and 

 2 — 5 lines wide, grass-like, membranaceous and deep green, obscurely 3-nerved. Sterile 

 flowers scarcely larger than the anthers of the rose, at length breaking connection with the 

 parent plant, rising to the surface, and, after floating around the fertile flower, quickly perish. 

 Fertile flowers on slender peduncles which vary in length with the depth of the water, usually 

 flexuous or spiral, rising to the surface of the water when ready to expand. Spathe about 

 half an inch long, membranaceous. Perianth white tinged with purple. Staminodia (or 

 abortive stamens) linear, alternating with the divisions of the perianth. Ovary linear, slender : 

 style none : stigmas large, oval, 2-cleft. 



Slow-flowing rivers and shallow bays : very common in the Hudson from the Highlands 

 upward ; also in the western part of the State. Fl. August. Fr. September - October. 

 This plant is so abundant in the shoal waters of the Hudson, that in many places, during the 

 months of August and September, it is difiicult to row a boat through it. There can no longer 

 be any doubt of its being the same as the European plant. Sir William Hooker examined 

 living North American specimens that were cultivated in the Glasgow Botanic Garden, and 

 found them to be identical with V. spiralis. It is generally believed that the roots of this 

 plant are the favorite food of the Canvass-back Duck, and give to the flesh of that bird its 

 delicious flavor. 



Order CXII. ORCHIDACEiE. Juss. The Orchis Tribe. 



Flowers irregular. Perianth of 6 segments in two series, the outer (calyx) 

 usually colored and petaloid like the inner ; the lowest one C^W) differing in 

 form from the others, and often spurred. The solitary fertile stamen (or in 

 Cypripedium the two fertile stamens) united with the style, and thus forming 

 the column : anther often deciduous. Pollen cohering in two or more masses, 

 which are either powdery or of the consistence of wax. Ovary cohering 

 with the tube of the perianth (inferior), mostly 6-ribbed and often twisted, 

 one-celled, with 3 parietal placentae, which are covered with ovules : style 

 forming part of the column : stigma a viscid concave spot in front of the 

 column. Seeds extremely numerous and minute, invested with a reticulated 

 coat. — Herbs of varied aspect, often with tuberous roots, and generally hand- 

 some flowers in spikes or racemes. 



For convenience I call the three outer leaflets of the perianth sepals, the two lateral of the inner series petals, and the 

 lowest one of the same series is named the lip. 



